Maintaining the Accuracy of a Sea Surface Height Climate Data Record from Multi-mission Altimeter Data

Wednesday, 17 December 2014: 5:15 PM
Brian D Beckley1,2, Richard D Ray2, Frank G Lemoine3, Nikita P Zelensky1, Xu Yang4, Gary T Mitchum5, Martina Ricko6, Shailen Desai7 and Shannon Thomas Brown7, (1)Stinger Ghaffarian Technologies Greenbelt, Greenbelt, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)NASA Goddard SFC, Greenbelt, MD, United States, (4)SGT INC., Greenbelt, MD, United States, (5)Univ South Florida, Saint Petersburg, FL, United States, (6)University of Maryland College Park, College Park, MD, United States, (7)NASA Jet Propulsion Laboratory, Pasadena, CA, United States
The determination of the rate of change of mean sea level (MSL) has undeniable societal significance. The measurement of geocentric sea level change from satellite altimetry requires an extreme stability of the altimeter measurement system since the signal being measured is at the level of a few mm/yr. Many of the obstacles previously impeding the measurement and validation of estimates of GMSL from satellite altimetry have been overcome (Fu and Haines, 2012). Nonetheless, measuring sea level rates at the precision required for climate science continues to be challenging for at least two reasons: (1) the Terrestrial Reference Frame (TRF) realizations are determined using space geodetic data over finite time spans, and must be periodically updated; (2) the dynamic nature of the Earth engenders global and regional variations in the geopotential which if not properly modeled ultimately cause errors in the computed sea level.

Recent developments in Precise Orbit Determinations (POD) due to in particular to revisions to the terrestrial reference frame (i.e. updates to ITRF2008, and the expected availability of ITRF2013) and the development of improved time variable gravity (TVG) models continue to provide improvements to the accuracy and stability of the POD that directly affect mean sea level estimates. Long-term and reliable MSL estimates that rely on data from multiple altimeter missions require the highest possible orbit accuracy and consistency in the use of applied geophysical models in POD computations. The stringent GMSL accuracy requirements are particularly essential for closure of the mass budget over the relative short time period where measurements from Jason-1&2, GRACE, and Argo are coincident.

In this presentation we describe the development, utility, and the accuracy maintenance of the MEaSURE’s TPJAOS V3.0 sea surface height Climate Data Record ( We provide an assessment of recent improvements to the accuracy of the 22-year sea surface height time series, describe continuing calibration/validation activities, and evaluate the subsequent impact on current global and regional mean sea level estimates.